New Forensic Method Reveals Hidden Traces in RDP-Based Cyberattacks

Cybersecurity researchers have developed sophisticated techniques to track attackers who use Remote Desktop Protocol (RDP) for lateral movement within compromised networks.

This emerging field of RDP forensics provides incident responders with powerful tools to reconstruct malicious activities and identify intrusion pathways, turning the attackers’ preferred remote access method into a detailed evidence trail.

Windows Event Logs Reveal Attacker Footprints

The cornerstone of RDP forensics lies in Windows Event Logs, which capture detailed records of remote access attempts.

Security professionals focus on Event ID 4624 (successful logons) and Event ID 4625 (failed logons) within the Security log.

However, Network Level Authentication (NLA) complicates this process by initially logging RDP connections as “Logon Type 3” (Network) rather than the expected “Logon Type 10” (RemoteInteractive).

The TerminalServices-RemoteConnectionManager log provides additional evidence through Event ID 1149, which records successful network connections to the RDP service.

Despite its misleading name, “User authentication succeeded,” this event only indicates someone reached the login screen, not a complete authentication.

The TerminalServices-LocalSessionManager log captures session lifecycle events, including Event 21 (session logon) and Event 24 (session logoff), providing precise timing information.

Bitmap Cache Analysis Reconstructs Attacker Activities

One of the most innovative techniques involves analyzing RDP’s bitmap cache, which stores small image tiles of the remote screen in files located at AppData\Local\Microsoft\Terminal Server Client\Cache\.

These cache files contain thousands of 64×64 pixel fragments that forensic analysts can reassemble to reconstruct what attackers viewed during their sessions.

Tools like BMC-Tools, RDPieces, and RdpCacheStitcher enable investigators to parse these cache files and piece together screen fragments.

In documented cases, analysts have successfully reconstructed entire sensitive documents and application windows that APT groups accessed via RDP, providing visual evidence of data exfiltration activities.

Registry Artifacts

Attackers often leave traces in Windows registry locations, particularly in HKCU\Software\Microsoft\Terminal Server Client\Servers and HKCU\Software\Microsoft\Terminal Server Client\Default, which maintains the Most Recently Used (MRU) lists of RDP connections.

These registry entries persist even after failed connection attempts, providing a historical record of targeted systems.

Device redirection artifacts offer unexpected evidence sources.

When attackers enable printer or drive redirection, Windows logs these mappings in TerminalServices-Printers and TerminalServices-DeviceRedirect logs.

In one notable case, an ex-employee’s redirected printer revealed their new employer’s network domain through the printer path \\NEWCORP-PRN001.newcompany.local\HP LaserJet 4200.

Memory forensics techniques can also recover clipboard data from the rdpclip.exe process, potentially revealing passwords and sensitive information copied during RDP sessions.

This comprehensive approach to RDP forensics demonstrates how cybersecurity professionals transform a common remote access tool into a detailed investigative resource, enabling organizations to trace attacker movements and strengthen their defensive capabilities.

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